1. Field of the Invention
The present invention relates to a control apparatus of a non-volatile memory which is built in an apparatus and an image forming apparatus and, more particularly, to a control method of a non-volatile memory which is built in, for example, a copying apparatus, a printer, or a facsimile (FAX).
2. Description of the Related Art
Hitherto, for example, in an image forming apparatus, respective items such as the number of prints, using time, and the like are measured and the measured value is stored into a non-volatile memory such as an EEPROM (Electrically Erasable and Programmable ROM). A maintenance such as exchange time, or repair of parts is performed with reference to the stored values. The EEPROM which is used as a non-volatile memory is a device in which the number of rewriting times is limited. The limited number of rewriting times is equal to about 10000 to 100000 times. Therefore, a method of controlling the non-volatile memory so that the number of rewriting times does not exceed such a limited number of rewriting times has been proposed. For example, such control that a plurality of storage areas for storing predetermined data are provided, a pointer to designate the storage area is provided, and when the data in one storage area reaches a predetermined value, the pointer is changed has been proposed (for example, refer to Japanese Patent Application Laid-Open No. H06-138730). A control method whereby timing for rewriting the non-volatile memory is controlled, thereby preventing the number of rewriting times from exceeding the limited number has also been proposed. For example, such control that when a predetermined amount of data is added to the data which is stored into the non-volatile memory, if a power supply to an apparatus main body is turned off, the non-volatile memory is rewritten has been proposed (for example, refer to Japanese Patent Application Laid-Open No. H05-249769).
However, depending on a using state of the user, there is a case where it is difficult to estimate the number of rewriting times of the non-volatile memory. For example, it corresponds to a case in an image forming apparatus in which a plurality of exchangeable cartridges adapted to form images are provided and a non-volatile memory is built in each cartridge. In such an image forming apparatus, it corresponds to a case where when an image formation is executed by using only a specific cartridge, the non-volatile memories built in other cartridges are also rewritten.
In such cases, in spite of a fact that toner consumption amounts of the cartridges which are not used for the image formation are smaller than that of the cartridge used for the image formation, the number of times of the rewriting operation which is executed to the non-volatile memory until the cartridge is exchanged increases. Since a using frequency of each of the cartridges having a possibility that they are not used for the image formation differs depending on the user, it is difficult to estimate the number of rewriting times of the non-volatile memory. The image forming apparatus with such a construction has been proposed in Japanese Patent Application Laid-Open No. 2001-215862. In such a case, in order to assure a reliability of the data which is stored into the non-volatile memory, it is necessary to use a non-volatile memory in which the limited number of rewriting times is larger than the number of rewriting times based on the general using state, or it is necessary to decrease the rewriting frequency so as not to exceed the limited number of rewriting times and use the non-volatile memory. However, there is a possibility that use of the non-volatile memory in which the limited number of rewriting times is large results in increase in costs. If the rewriting frequency is simply decreased, a possibility that the data whose writing is not finished yet is lost due to the attaching/detaching operation of the cartridge, a power-off of the image forming apparatus, or the like increases.
The invention is made by paying attention to such problems and it is an object of the invention to provide a control apparatus of a non-volatile memory and an image forming apparatus, in which a reliability of data which is written into the non-volatile memory does not deteriorate in various using states.